Efficient, controlled coupling to and conveyance of optical energy through apertures is an important aspect of many optical measurement instruments. This observation is especially applicable to confocal and interferometric confocal microscopy where a high through-put, i.e., high data rates, is required while maintaining high lateral and longitudinal spatial resolutions and high signal-to-noise ratios. This observation is even more applicable to near-field microscopy which employs apertures smaller than a free space optical wavelength of an optical beam, herein after referred to as sub-wavelength apertures, to achieve imaging with high lateral spatial resolution. The low optical efficiency, typically of the order 10−4 or lower, of sub-wavelength probes used as near-field scanning probes can have a particularly negative impact on signal-to-noise ratios and measurement bandwidth.